Question

我正在尝试通过验证数据库中已有的电子邮件和密码来创建登录页面。但是，会发生致命异常。

这是我的LoginActivity.java，myDbHelper.java，activity_login.xml和logcat错误。

logcat错误如下：

FATAL EXCEPTION:main
    Process:no.nordicsemi.android.nrftoolbox,PID:9052
    java.lang.IllegalStateException:
    Could not
    execute method for android:onClick
    at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
    at android.view.View.performClick(View.java:4785)
    at android.view.View$PerformClick.run(View.java:19888)
    at android.os.Handler.handleCallback(Handler.java:739)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:135)
    at android.app.ActivityThread.main(ActivityThread.java:5276)
    at java.lang.reflect.Method.invoke(
    Native Method)
    at java.lang.reflect.Method.invoke(Method.java:372)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:911)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:706)
    Caused by:java.lang.reflect.InvocationTargetException
    at java.lang.reflect.Method.invoke(
    Native Method)
    at java.lang.reflect.Method.invoke(Method.java:372)
    at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
    at android.view.View.performClick(View.java:4785) 
    at android.view.View$PerformClick.run(View.java:19888) 
    at android.os.Handler.handleCallback(Handler.java:739) 
    at android.os.Handler.dispatchMessage(Handler.java:95) 
    at android.os.Looper.loop(Looper.java:135) 
    at android.app.ActivityThread.main(ActivityThread.java:5276) 
    at java.lang.reflect.Method.invoke(
    Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:372) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:911) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:706) 
    Caused by:android.database.sqlite.SQLiteException:near ".":

    syntax error(code 1):,while compiling:select *
    from contacts
    where email = android.support.v7.widget.AppCompatEditText

    {
        1d 2 b15f4 VFED..CL ........ 0, 72 - 1080, 208 #7f 090085 app:
    id / editText_mail
    }

    at android.database.sqlite.SQLiteConnection.nativePrepareStatement(
    Native Method)
    at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
    at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
    at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
    at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
    at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
    at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
    at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1316)
    at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1255)
    at no.nordicsemi.android.nrftoolbox.myDbAdapter.getEmail(myDbAdapter.java:208)
    at no.nordicsemi.android.nrftoolbox.LoginActivity.login(LoginActivity.java:41)

我的LoginActivity.java：

public class LoginActivity extends AppCompatActivity {

    TextView email;
    TextView pass;

    private no.nordicsemi.android.nrftoolbox.myDbAdapter mydb;

    @Override

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
        email = (TextView) findViewById(R.id.editText_mail);
        pass = (TextView) findViewById(R.id.editText_pass);
        mydb = new no.nordicsemi.android.nrftoolbox.myDbAdapter(this);

    }

    public void register(View v) {
        Intent goToSecond = new Intent();
        goToSecond.setClass(this, Register_Page.class);
        startActivity(goToSecond);
    }

    public void login(View v) {
        Cursor c1 = mydb.getEmail(email);
        Cursor c2 = mydb.getpass(pass);
        if (c1 != null & c2 != null) {
            Intent goToSecond = new Intent();
            goToSecond.setClass(this, Profile.class);
            startActivity(goToSecond);
        } else
            message(getApplicationContext(), "not valid user");
    }
}

myDbHelper.java（getEmail和getpass方法）如下：

 public Cursor getEmail(TextView email)
    {
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor= db.rawQuery( "select * from contacts where email="+email+"",null);
        return cursor;
    }
    public Cursor getpass(TextView pass)
    {
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor= db.rawQuery( "select * from contacts where password="+pass+"",null);
        return cursor;
    }

导致应用崩溃的原因是什么？可能的错误在哪里？

我做了建议的更改。但现在logcat错误显示：

Caused by: android.database.sqlite.SQLiteException: near "@gmail": syntax error (code 1): , while compiling: select * from contacts where email=kingervinny@gmail.com

我怎样才能纠正这个？

Answer 1

EditText email = (EditText) findViewById(R.id.editText_mail);
EditText  pass = (EditText) findViewById(R.id.editText_pass);
Cursor c1 = mydb.getEmail(email.getText());
Cursor c2 = mydb.getpFass(pass.getText());

AND  
 Cursor cursor= db.rawQuery( "select * from contacts where email='"+email.getText().toString()+"'",null);

Cursor cursor= db.rawQuery( "select * from contacts where password='"+pass.getText().toString()+"'",null);

Answer 2

纠正 SELECT 声明。

SQLiteException：near“。”：语法错误（代码1）:,编译时：

使用 getText().toString() 。您的 SELECT 语句将为。

 Cursor cursor= db.rawQuery( "select * from contacts  where email='"+email.getText().toString()+"'",null);

并且

 Cursor cursor= db.rawQuery( "select * from contacts  where password='"+pass.getText().toString()+"'",null);

Answer 3

导致应用崩溃的原因是什么？可能的错误在哪里？

导致email和pass问题，因为sql查询始终为字符串，而email和pass不是String，而是{{1因此崩溃

将TextView更改为：

myDbHelper.java

无法执行android的方法：onClick？

3 个答案: